SEM images of ((a) and (b)) pure PANI at different magnifications. Both of them show the aggregations of nanofibers and nanoparticles mixture; SEM images of (c) GO, (d) GO/PANI. Each of them shows a 3D porous network structure; SEM images of ((e) and (f)) graphene/PANI at different magnifications. Each of them shows that graphene is evenly coated by PANI.